SEASONS IN BULGARIA
Bulgaria includes 31% lowlands (0–200 m), 41% hills (200–600 m), 25% highlands (600–1,600 m), and 3% mountains (>1,600 m) (2). The country is split into northern and southern Bulgaria by the Balkan Mountains. The climate is continental in the north and close to Mediterranean in the South. The annual amount of precipitation is between 500 and 650 mm, with precipitation ranging from 440 to 1020 mm. The highest monthly values are measured in June (at some places in May), with mean totals between 55 and 85 mm. February (or March) is the driest month, with mean totals between 30 and 45 mm . The continental influence, stronger during the winter, produces abundant snowfall; the Mediterranean influence increases during the summer and produces hot, dry weather. The barrier effect of the Balkan Mountains is felt throughout the country: on the average, northern Bulgaria is about one degree cooler and receives about 192 more millimetres of rain than southern Bulgaria . The monthly mean temperature varies from -10.9 to 3.2 C in January and from 5.0 to 25.0 C in July. The highest readings are usually taken in the towns of Rousse and Silistra, sometimes reaching above 35°C . Bulgaria has a temperate-continental climate with moderate features which is characteristic for Central Europe, with hot summers, long, cold winters and very distinct seasons. Abundant snowfalls may occur throughout the country from December to mid-March, especially if you are in the mountainous areas of Bulgaria. The country occupies the southernmost part of the continental climatic zone, with small areas in the south falling within the Mediterranean climatic zone. The continental zone is predominant, because continental air masses flow easily into the unobstructed Danubian Plain. The continental influence, stronger during the winter, produces abundant snowfall; the Mediterranean influence increases during the second half of summer and produces hot and dry weather. Another important factor is the relief. The Bulgarian mountains and valleys act as barriers or channels for air masses, causing sharp contrasts in weather over relatively short distances. The Balkan Mountains form a barrier which effectively stops the cool air masses coming from the north and the warm masses from the south. The barrier effect of the Balkan Mountains is felt throughout the country: on the average, northern Bulgaria is about one degree cooler and receives about 192 mm more rain than lowlands of southern Bulgaria. The Rilo-Rhodope Massif bars the warm Mediterranean air masses and limits the Mediterranean influence to the southern valleys of the rivers Struma, Mesta, Maritsa and Tundzha, despite the close proximity of the Aegean Sea. Bulgaria is subdivided into five climatic zones: continental zone (Danubian Plain, Pre-Balkan and the higher valleys of the Transitional geomorphological region); transitional zone (Upper Thracian Plain, most of the Struma and Mesta valleys, the lower Sub-Balkan valleys); continental-Mediterranean zone (the southernmost areas of the Struma and Mesta valleys, the eastern Rhodope Mountains, Sakar and Strandzha); Black Sea zone along the coastline with an average length of 30–40 km inland; and alpine zone in the mountains above 1000 m altitude (central Balkan Mountains, Rila, Pirin, Vitosha, western Rhodope Mountains, etc.). Despite the large distance, the most important climate-forming factor is the Atlantic Ocean through the atmospheric circulation of the Icelandic cyclone and the Azores anticyclone, which bring cool and rainy weather in summer and relatively mild weather with abundant snowfall in winter. The influence of the Mediterranean Sea is strongest in the southern parts of Bulgaria, mainly through the Mediterranean cyclones. Due to its small area, the influence of the Black Sea only affects a 30–40 km long strip along the coastline, mainly in summer, when the daily breeze circulation is most pronounced. The warmest parts of Bulgaria are in the southwest, where the Mediterranean climate effects in the valleys are particularly strong. The seaside has a mild subtropical climate heavily influenced by the Black Sea’s presence. The plains and lowlands in the north and south experience continental weather (with the south usually a bit warmer) and the mountains are known for their Alpine climate conditions. The highest temperature ever recorded in Bulgaria is 45.2 °C, while the lowest record stands at −38.3 °C. That’s a staggering difference of 83.5 degrees! The mean annual temperature in Bulgaria is 10.6 °C and varies from –2.9 °C at the nation's highest peak Musala to 13.9 °C at the town of Sandanski in the southern Struma valley. The average temperature in the Danubian Plain is 11.4 °C, in the Upper Thracian Plain — 13.9 °C, in the lower mountains — 8.1 °C and in the higher mountains — 2.4 °C. The highest absolute temperature was measured at the town of Sadovo in 1916 — 45.2 °C; the lowest absolute temperature was measured at the town of Tran in 1947 — –38.3 °C. The highest temperature in the lowlands and the hilly regions is in June, while in the higher mountains the warmest month is August. The lowest temperature is measured in January and February, respectively. Many valleys experience regular temperature inversions and fogs in winter. The country's lowest absolute temperature was measured during an inversion in the Tran valley. The average precipitation in Bulgaria is about 670 mm more in the mountains (up to 1000 mm and more) and less on the coast (around 400-600 mm). It can rain throughout the year; in general, winter is the driest season. In summer, showers and thunderstorms are common, especially in the mountains. Annual precipitation varied considerably from year to year in the 20th century. Climate in Bulgaria became drier at the end of the 20th century. During the last decade however, precipitation totals have increased. Heavy rains caused severe floods damaging various socioeconomic sectors . An investigation of change in snow cover (maximum depth and snow cover duration) over the 1931–2000 period was carried out at sixteen climate stations located in mountainous areas of Bulgaria. The mountain climate has been characterized by widespread warming and decreased winter precipitation over this period. However, there was no evidence of similar large-scale reductions in snow depth or snow cover duration: some sites showed significant decreases in snow cover, some no change, while others showed significant increases. Further analysis is required to understand the reasons for the varied response of snow cover to a changing climate. The mountain climate is characterized by warming in all regions with significant reductions in winter precipitation in many mountain areas. Statistically significant reductions in annual precipitation for several Bulgarian mountain stations were reported before. Similar findings have been reported from other regions of European. Decreasing trends in annual and seasonal precipitation have been observed in the central and southern areas of Italy, for instance, especially during the second half of the 20th century. It is uneven in terms of seasons and territory. In northern Bulgaria the highest precipitation is in May–June, while in southern Bulgaria it is in winter. The average amount of precipitation also varies in term of altitude — from 450–850 mm in the plains to 850–1200 mm. The lowest mean precipitation is in the eastern part of Dobrudzha and the Burgas Plain (450 mm) and in the area between Plovdiv and Pazardzhik (500 mm); the highest rainfall falls in the mountains — the Petrohan Pass in the western Balkan Mountains and Zlatograd in the Rhodope Mountains. The highest annual rainfall was measured in 1957 in the upper valley of the river Ogosta in the western Balkan Mountains (2293 mm); the highest daily rainfall was recorded at Saints Constantine and Helena resort (342 mm) near Varna in 1951. The total annual amount of the rainfall is 74 billion km3; of them 70% evaporate, 20% flow into the rivers and 10% soak into the soil. Most of the country is affected by droughts in June and August. The snow cover lasts from 20–30 days in the lowlands to 9 months in the highest mountains. Bulgarian mountains and valleys act as barriers or channels for air masses, causing sharp contrasts in weather over relatively short distances. The continental zone is slightly larger, because continental air masses flow easily into the unobstructed Danubian Plain. The continental influence, stronger during the winter, produces abundant snowfall; the Mediterranean influence increases during the summer and produces hot, dry weather. The barrier effect of the Balkan Mountains is felt throughout the country: on the average, northern Bulgaria is about one degree cooler and receives about 192 more millimeters of rain than southern Bulgaria. Because the Black Sea is too small to be a primary influence over much of the country's weather, it only affects the immediate area along its coastline. Bulgaria is not a huge country even by European standards, so weather variations between the different regions are usually no more than 6-7 °C. That is if you exclude the high reaches of the mountains, where the altitude makes it dramatically colder. Bulgaria’s climate is a combination of continental and Mediterranean influences, which means the country has four quite well-defined seasons (spring, summer, autumn and winter) and temperatures vary dramatically in different times of the year. In general, you can expect summers to be quite hot and dry and winters to be snowy and freezing, with spring and autumn providing a transition between the two. After the harshness of winter, the blossom of trees signals the beginning of spring at some point in March. As the temperatures gradually increase and the remaining snow melts, the fields and meadows are at their greenest and the landscapes can be incredibly scenic. SPRING In spring, you can expect temperatures of 15-25 °C in Bulgaria, steadily increasing from March to June. There’s less sunshine than in the summer, but normally it doesn’t rain a lot either. The weather can be quite foggy and turbulent in general, especially in March, which has a reputation for being unpredictable. Mountains above 2000 metres remain snowy until June-July, so hiking is a bit challenging in spring, and the waters of the Black Sea are too cold for comfortable bathing until mid-June or so. SUMMER Bulgarian summer rolls around with the beginning of June, when temperatures reach above 30 °C. July and August are the hottest months and the sun can be quite strong at midday indeed. Temperatures above 35 °C are not uncommon and it can sometimes be nearing 40 °C! Summer days are usually clear and sunny, though when it rains, it pours in the form of brief but violent summer storms . This may seem like a whole lot of heat, but thankfully, Bulgaria offers a lot of ways to escape. The gentle breeze of the seaside and the refreshing Black Sea (which in summer is in the 20s) make for a very pleasant summer holiday. The mountains are at their most inviting with their cooler temperatures and chilly nights around the fire! AUTUMN Summer tends to end by mid-September, when temperatures drop a bit and the days get shorter. September and October can still be quite warm and pleasant and in general autumns are not particularly rainy compared to the rest of Europe. Autumn is also the season when grapes are harvested to make wine and grannies prepare supplies for the coming winter – you cannot mistake the trademark smell of roasting peppers in September and October! Bulgarian autumn boasts temperatures around 10-25°C, gradually decreasing as winter approaches by the end of November and early December. Early September may still be a good time to hit the seaside or ascend into the mountains, but by October it usually gets too cold for that. WINTER Winters starts with December, when temperatures begin to drop below zero. The end of December usually brings the first snow of the year and until March it usually snows rather than rains. Though it can stay below zero for weeks in a row (temperatures around -5 to -15°C are common), the days can still be regularly clear and sunny. In fact, for many places in Bulgaria, winter is one of the driest seasons. Clear and sunny with below zero temperatures keeping snow on the ground for a long time – sounds like perfect skiing and snowboarding conditions. And indeed, late December to March (whenever there’s snow) is Bulgaria’s winter season, when resorts like Bansko and Borovets attract local and international tourists to their ski trails. Resources: http://wikipedia.org http://weatheronline.co.uk http://climatechangepost.com